. >>> canada pulled the last of the combat troops out of afghanistan this week. this brings us to our question of the week. how many nations still have combat troops in afghanistan as part of the international security assistance force? is it a, 6, b, 16, c, 26 or d 46. stay tuned and we'll tell you the correct answer. go to cnn.com/gps for ten more questions. while you're there, make sure you check out our website, the global public square where you'll find smart interviews and essays and takes by our favorite experts. you will also find all of our gps shows. if you miss one, you can click and watch. don't forget, you can follow us on twitter and facebook. this week's book of the week is the last narco. it takes you deep inside the life of a man known as elchapo now that bin laden is dead, this mexican drug king pin is the number one most wanted man in the world. he's also on forbes list of the world top billionaires, it's a fascinating look at the man, the operation and international hunt for him. very well written. and now for the last look. we often think our